This invention relates to a light source for photography, and more particularly to a ring light converter for a conventional electronic flash unit, such as a strobe light.
In photography, it is common to utilize an artificial light source for indoor pictures or when there is insufficient natural light. Typically, most modern day cameras utilize electronic flash units, such as strobe lights. However, such electronic flash units are attached to the camera at a singular position spaced from the lens. As a result, in taking pictures at relatively short distances, the electronic flash unit will produce a shadow on the subject and thus cause a loss of detail of the subject.
To avoid such problems, photoflash and electronic flash units known as ring lights have been developed. These units comprise a flash tube formed in a circular shape and adapted to be mounted on a camera so as to encircle the lens of the camera and thereby provide a source of nearly constant illumination around the periphery of the lens. However, such ring lights are expensive due to the formation of the circular light source therein, and are generally fragile and difficult to work with. They also require large power sources, which increase the weight of the unit and make them difficult to carry and use.
U.S. Pat. No. 3,474,242 teaches a photographic ring light which attempts to alleviate the aforementioned problems. In that patent, a horse shoe-like casing is disclosed to provide a gap therein. A flash lamp is disposed in a socket within the gap of the casing, and by means of dimensioning the casing as well as utilizing a plurality of reflecting surfaces, such as serrations, the light from the flash lamp is transmitted around the casing and reflected outwardly therefrom.
Although the aforementioned patent eliminates the necessity of an active circular tube, the "passive" ring light described obviously cannot produce a uniform source of light completely around the lens. Since the casing is incomplete because of the gap, the housing essentially represents a "C" configuration and cannot provide a complete 360.degree. illumination around the lens. Additionally, because of its particular configuration, the referenced ring light cannot inherently provide uniform illumination around the lens.
As a result, the aforereferenced patent describes that the housing is shaped to increase in thickness in the vicinity of the light source both in a radial dimension and in a dimension parallel to the lens axis to thereby compensate and increase the amount of light coupled from the light source into the opposed spaced end faces of the housing. Furthermore, the rear face includes a plurality of serrations which serve as individual reflecting surfaces for the light transmitted through the casing from the source. Also, opposed end faces adjacent to the light source have serrated surfaces for transmitting the light into the casing. As a result of such modifications in the dimension as well as the formation of the serrations, the aforementioned unit is complex to utilize, extremely expensive to make, is cumbersome and not very practical. It cannot provide a uniform light throughout its area, and cannot provide a complete 360.degree. illumination around the lens. Furthermore, it utilizes its own light source, flash bulb and necessary electrical components, which further complicates matters in that it still requires the necessity for a user to purchase two independent flash units, one for conventional use and one for ring light use. There is also the high cost of flash bulbs which must be replaced with each picture.